Structure and Geometry of the Eureka Valley Extensional Basin, Eastern California, from Gravity Modeling
Landreneau, Lauren Ashley
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Eureka Valley, situated in eastern California, is a north-northwest trending extensional basin characterized by northeast striking, northwest dipping normal faults that serve to displace offset from the Hunter Mountain – Panamint Valley – Saline Valley fault system to the Death Valley – Furnace Creek – Fish Lake Valley fault system. To evaluate the subsurface geometry of Eureka Valley a detailed relative gravity survey was conducted and a residual complete Bouguer anomaly map was produced and inverted for depth. Geologic cross-sections and a fault model were used to forward model the gravity data. A fault displacement budget, with respect to the extension direction, allows for the trigonometric determination within the basin. Estimated minimum vertical displacements range between 3.8 and 4.1 km were based on restoring basement depths to a pre-extensional datum. Using the regional extension direction of N65W and a fault dip of 60˚, we calculated an aggregate horizontal extension of 4 km across Eureka Valley. With extension starting after 4 Ma, the average displacement rate is 1.0 mm/yr.